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From: Peter Zijlstra <peterz@infradead.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Xi Ruoyao <xry111@mengyan1223.wang>,
	Jiri Kosina <jikos@kernel.org>, Kees Cook <keescook@chromium.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Ingo Molnar <mingo@kernel.org>,
	Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
	Borislav Petkov <bp@alien8.de>, Len Brown <lenb@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
	Tony Luck <tony.luck@intel.com>,
	Bob Moore <robert.moore@intel.com>,
	Erik Schmauss <erik.schmauss@intel.com>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Daniel Bristot de Oliveira <bristot@redhat.com>,
	Juergen Gross <jgross@suse.com>
Subject: Re: [PATCH] x86/asm: Move native_write_cr0/3() out of line
Date: Wed, 10 Jul 2019 22:02:40 +0200	[thread overview]
Message-ID: <20190710200240.GR3402@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <alpine.DEB.2.21.1907102140340.1758@nanos.tec.linutronix.de>

On Wed, Jul 10, 2019 at 09:42:46PM +0200, Thomas Gleixner wrote:
> The pinning of sensitive CR0 and CR4 bits caused a boot crash when loading
> the kvm_intel module on a kernel compiled with CONFIG_PARAVIRT=n.
> 
> The reason is that the static key which controls the pinning is marked RO
> after init. The kvm_intel module contains a CR4 write which requires to
> update the static key entry list. That obviously does not work when the key
> is in a RO section.
> 
> With CONFIG_PARAVIRT enabled this does not happen because the CR4 write
> uses the paravirt indirection and the actual write function is built in.
> 
> As the key is intended to be immutable after init, move
> native_write_cr0/3() out of line.
> 
> While at it consolidate the update of the cr4 shadow variable and store the
> value right away when the pinning is initialized on a booting CPU. No point
> in reading it back 20 instructions later. This allows to confine the static
> key and the pinning variable to cpu/common and allows to mark them static.
> 
> Fixes: 8dbec27a242c ("x86/asm: Pin sensitive CR0 bits")
> Fixes: 873d50d58f67 ("x86/asm: Pin sensitive CR4 bits")
> Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
> Reported-by: Xi Ruoyao <xry111@mengyan1223.wang>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Tested-by: Xi Ruoyao <xry111@mengyan1223.wang>

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

  parent reply	other threads:[~2019-07-10 20:03 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-08 16:27 [GIT PULL] x86/topology changes for v5.3 Ingo Molnar
2019-07-09  1:45 ` pr-tracker-bot
2019-07-09 21:20 ` Linus Torvalds
2019-07-09 21:26   ` Linus Torvalds
2019-07-09 21:45     ` Linus Torvalds
2019-07-09 22:00       ` Linus Torvalds
2019-07-09 22:07         ` Linus Torvalds
2019-07-09 22:27         ` Thomas Gleixner
2019-07-09 23:00           ` Thomas Gleixner
2019-07-09 23:17             ` Thomas Gleixner
2019-07-10  0:31               ` Kees Cook
2019-07-10 11:27                 ` Xi Ruoyao
2019-07-10 12:01                   ` Xi Ruoyao
2019-07-10 12:19                     ` Thomas Gleixner
2019-07-10 12:31                       ` Jiri Kosina
2019-07-10 13:21                         ` Peter Zijlstra
2019-07-10 13:27                           ` Jiri Kosina
2019-07-10 13:28                             ` Jiri Kosina
2019-07-10 13:31                               ` Xi Ruoyao
2019-07-10 13:25                         ` Xi Ruoyao
2019-07-10 13:44                           ` Peter Zijlstra
2019-07-10 14:03                             ` Thomas Gleixner
2019-07-10 14:26                               ` Thomas Gleixner
2019-07-10 14:22                             ` Jiri Kosina
2019-07-10 14:26                               ` Peter Zijlstra
2019-07-10 15:13                                 ` Thomas Gleixner
2019-07-10 15:58                                   ` Xi Ruoyao
2019-07-10 19:42                                     ` [PATCH] x86/asm: Move native_write_cr0/3() out of line Thomas Gleixner
2019-07-10 19:59                                       ` Kees Cook
2019-07-10 20:00                                         ` Thomas Gleixner
2019-07-10 20:02                                       ` Peter Zijlstra [this message]
2019-07-10 20:19                                       ` [tip:x86/urgent] x86/asm: Move native_write_cr0/4() " tip-bot for Thomas Gleixner
2019-07-10 14:44                               ` [GIT PULL] x86/topology changes for v5.3 Xi Ruoyao
2019-07-11  7:11                               ` Nadav Amit
2019-07-11  7:16                                 ` Thomas Gleixner
2019-07-11  8:01                                 ` Peter Zijlstra
2019-07-11 15:08                                   ` Kees Cook
2019-07-11 17:09                                     ` Nadav Amit
2019-07-10  0:59             ` Linus Torvalds
2019-07-10  1:08               ` Linus Torvalds
2019-07-10  3:21                 ` Linus Torvalds
2019-07-10  5:15                   ` Linus Torvalds
2019-07-10  5:33                     ` Kees Cook
2019-07-10 18:40                     ` Linus Torvalds
2019-07-10 10:03             ` Rafael J. Wysocki

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